Electric telegraphy.



PATENTED AUG. 8, 1905.

A. MUIRHEAD. ELECTRIC TELEGRAPHY.

APPLICATION FILED 00114, 1904.

UNITED STATES PATENT orrion.

ELECTRIC TELEGRA'PHY.

Specification of Letters Patent.

Patented Aug. 8', 1905.

Application filed October 14, 1901- fi fi 7 3 To all whom it may concern:

Be it known that I, ALEXANDER MUIRHEAD, residing at Shortlands, in the county of Kent, England, have invented new and useful Improvements Relating to Electric Telegraphy, of which the following is a specification.

My invention relates to the transmission, reception, and retransmission of telegraphic signals, more especially in connection with submarine-cable or like circuits where the arriving impulses are of a feeble character; and it consists in so employing and arranging certain electrical instrumentalities that a novel system of transmission and retransmission is produced and whereby an increase of speed in working is obtained and whereby the necessity for more or less complicated mechanical or electrical apparatus at the intermediate stations is obviated and other attendant advantages secured.

As is well known, signaling through submarine telcgraph-cables is effected by making asuccession of contacts with battery and earth in accordance with the Morse code. Currents of each sign, positive or negative, as the case may be, are sent into the cable in order to deflect the index of a receiver to one side or the other of its Zero position; but every application of the battery to the cable to produce a single deflection at the distant end has hitherto been of equal length or duration though varying in polarity.

It has heretofore been deemed impracticable in the present system of cable telegraphy with condensers or transformers to apply a battery to a cable for more than the time required to produce an excursion of the signal-coil from the zero and back again because of the gradual return to Zero and the deflection in the opposite direction which takes place on the cessation of the battery'- contact so prolonged.

By my present invention I show how to utilize, in the siphon-recorder system of working, battery-contacts which vary in duration to produce at the receiving end of the line deflections on the receiving instrument of coresponding varying lengths or duration, and thereby to secure attendant advantages.

Intransmitting impulses into a cable either a hand-key or an automatic transmitter is employed. In the specification of prior Letters Patent granted to me in the United States, No. 577,53 dated February 23, 1897, I have described an automatic transmitter for this purpose.

Impulses of equal duration passed into a cable as aforesaid are usually received upon a siphon-recorder, which, as is well known, consists ofa delicately suspended or pivoted coil located in a magnetic field, the arriving impulses passing through such coil to earth. Thus each arriving impulse causes the coil to swing in one direction or the other, dependiug upon the polarity of the particular impulse. Attached to this coil is a glass siphon, the shorter leg of which dips into an ink-reservoir, while the longer leg rests or vibrates upon a paper strip which is drawn beneath it continuously.

In retransmitting from one section of cable to another a relay analogous in construction to a siphon-recorder is employed; but the recordercoil instead of operating an ink-siphon moves a contact-tongue upon or against local relay-contacts, thereby making or breaking, as the case may be, either the retransmitting battery-circuit in connection with the next section of cable or a local-battery circuit whereby in turn the retransmitting or equivalent contacts are made.

In order that my invention may be more clearly understood and readily carried into effeet, I will proceed to describe the same more fully with reference to the accompanying drawings, wherein Figures 1 to 7 are reproductions of certain signals from a siphon-recorder explanatory of my invention. Fig. 8 is a diagram representing the instrumentalities and connections at three cable-stations, together with two connecting-cables. Fig. 9 is a similar diagram illustrating duplex connections at one cable-station, and Fig. 10 shows a modified form of siphon-recorder coil.

I will proceed first to describe fully my new system of cable transmission.

The letter s, for example, has heretofore been signaled by making three successive contacts of equal duration with one pole of a battery, each followed by contact with earth, and the letter o by making the same succession of contacts with the other pole of the battery and earth. Such a succession of contacts with battery and earth made at one end-of the cable produces a corresponding successionof deflections'of the signal-coil at the distant end of the cable, the letter s appearing as Fig. 1 and the letter o as Fig. 2, provided the rate of signaling is sufliciently slow to allow the received current for each of the three contacts with battery and earth to arrive at its maximum strength and then to fall back to zero.

currents or impulses run into each other more or less at the receiving end and form one wavy deflection of the receiver-coil, as illustrated by Figs. 3 and 4., the speed of case of Fig. 3 being slower than that of Fig. 4. In practice when it is requisite to work a cable at the highest speed possible the rate adopted is such that the arriving signals are of the character illustrated by Fig. 4, an experienced operator deciphering Fig. {i as being equivalent to Figs. 1 and 201' 3z'. a, as representing the word so; but with the arrangements hitherto in vogue any prolongation of the battery-contact with the cable would only produce a signalsimilar to that depicted in Fig. 5, (or of course on the opposite side of the zero line depending on the pole of the battery,) which would cause confusion in the retransmission, there being a full initial deflection followed bya slow return to zero anda reverse deflection ward. Fig. 5 is not a workable signal, and neither it nor Figs. 3 or 4 would be of any use for making relay-contacts for retransmitting into the next section of cable. Consequently elaborate means, both mechanical and electrical, have been devised for transforming for relay purposes an arriving signal, such as Figs: 3 ore, into a succession of separate contacts with battery of equal duration. My present invention consists in employing such apparatus and so arranging the connections thatalthough condensers or transformers are employed in the sending-circuit or in the receiving-circuit, or in both, there is a complete conductive circuit through the conductor and through the receivinginstrument of every section of cable between the earth at the sending end and the earth at the receiving end. This renders it; possible that on inserting an electromotive force at one end of any section of cable the index of the receiver (whether recorder or relay) at the other end of that section is deflected to a given constant distance from its zero-line as long as the electromotive force is applied, and thissteady deflection may be continued to represent atv .the receiving end two, three, four, five, or .1 more elementary indications of" one polarity on the receiver, the letters s and so long as-the electromotive force is applied,

with the Morse code is such that in the formation of letters represented bytwo or more successive deflections of the receiving instrument in one direction in lieu of a succession of contacts withbattery of equal duration signaling in the- (on the opposite side) after-- (three in the illustrated cases of the letters 7 1 7:

s and 0 )one prolonged contact corresponding in period or duration to the succession of elementary indications of like sign of which the one letter is composed is made use I of to produce a similarly-prolonged signal on either side of the zero-line at the receivingstation such', for example, as the shapes shown in Fig. 6. It follows, therefore, that the similarly-prolonged contact made by the v relay-tongue at every intermediate station in the sending-circuit connected therewith pro-' ing number of elementary contacts required by the system of transmission which is at present adopted on cables.

Without the complete conductive circuit 3 from end to end of a cable when condensers or transformers are employed the current received is transient-2'. a, one that rises to I a maximum and then dies away. By superposing a properly-regulated complete conductive circuit upon the ordinary conditions of transmission with condensers or transformers the'received current, it will be seen,

' can be made to rise as rapidly to the same maxi mum and to keep at thatstrength aslong as the electromotive force which created it is applied 1 atthe sendingend of the cable. Both the sendj ing and receiving circuits should amount to circuits of pure resistance, so that the electrical changes created therein may take place as rapidly as possible and the speed oftransmission therefore-be the quickest possible. Moreover, in order to facilitate the regulation of the working of a number'of cables joined up in series in accordance with' this invention 'the circuits must also be designed in such manner that all the necessary "curbing of the received currents is done or can be controlled lat the receiving end of each section of cable,

n I pearing as illustrated in Fig. 6, and there is practically no a limit to this steady deflection and there mustalso be practical immunity from earth currents in that part of the circuit in which the receiving instrument is placed. In order to obtain the maximum speed of transmission and as large signals as possible,

it is essential that there should bean efiectplex or duplex.

ive discharge-circuit-c'. a, one of low retardation and resistance between the-cable and earth at the sending end whether on. sim- On simplex whenever it is possible thedirect application of the-battery to the cable is preferable to all other arrangements of the sending-circuit in carrying l l l.

out this invention.

After these preliminary explanatory remarks it will be possible to follow the diagram, Fig. 8, which illustrates transmission at the intermediate stations.

veasoe a in one direction of an installation on the simplex system. I being the initial station, II the intermediate station, and III the final station. It will be understood that in order to permit of simplex transmission in both di rections the apparatus will have to be duplicated at every intermediate station and each set of apparatus provided with an automatic switch, or each section of cable may be duplexed in the usual way.

1 and 2 represent the two cables. 3 and 3 are the sending-condensers, and 4 and 4 the receiving-condensers. 5 and 5 are the transmitting-batteries. 6, 7, 8, and 9 and 6 7, 8, and 9 are their respective terminals, and L and E are the line and earth tongues, respectively.

At the initial station when it is desired to produce at the intermediate station prolonged deflections-such, for example, as those shown in Figs. 6 or 7a succession of positive or negative currents of equal duration, but at such speed that such currents sufficiently run into each other at the receiving end, may be sent into the first section of cable by an automatic transmitter or by means of a hand signaling-key; but I prefer to send into the first section of cable positive and negative currents of varying duration in order to obtain full advantage from the beginning of the increased speed and from the lessened disturbance of the duplex balance which result from my new mode of transmission. In Fig. 8 I have illustrated one means of effecting this. 10 represents an automatic transmitter, of which 11 and 12 are the two contact-levers thatare operated by the mechanism of the transmitter in accordance with the holes in the perforated slip. 13 is a cam-wheel which is driven by the motor of the transmitter. 14 and 15 are two polarized relays connected up to the two contact levers 16, as shown. On the cam-wheel 13 rides a contact-lever 17, which closes and opens the circuit of a battery 18 thr0ugh the relays 14 and 15 once during every revolution of the cam 13 and is adjusted to close the batterycircuit a short time after the return of either of the levers 1112 to the back-stops 19 20 from making contact with the batterystops 21 22. The tongues of the relays 14 and 15 are connected to line and earth, respectively, and the limiting-stops 6, 7, 8, and 9, between which the relay-tongues play, are connected to the two poles of the line-battery 5, respectively. On the deflection of either of the levers 11 or 12 of the automatic transmitter 10 (the lever 11 is shown deflected) the tongue of the corresponding relay 14 or 15 is deflected, and the corresponding pole of the line-battery 5 is thereby applied and kept applied to the cable until the cam-wheel 11 and 12 and to a battery reset the tongue, which was deflected. A

' succession of deflections of either of the levers 11 or 12 will produce a permanent deflection of the tongue of the corresponding relay 14 or 15 instead of a succession of deflections, because the camwheel 13 is adjusted not to bring the lever 17 which rides on it, into contact with the contact-stop of the battery 18 until after the lever 11 or 12 has left the back-stop 19 or 20 on its way to make the succeeding contact with the batterystops 21 or 22. In order that the positive and negative currents of varying duration thus sent into the cable may produce. at the distant end thereof a deflection of the recorder or relay coil, and consequently the tongue or siphon, for a period corresponding to that of the battery-contact and so remain until such contact is broken, and thereby producing indications such as those depicted in Figs. 6 and 7 and without a final kick, as illustrated by Fig. 5, and also in order to obtain the right amount of such deflection, I connect across the sending-condenser 3, when one is employed. a shunt 23 of low resistance and in addition a shunt 23 of high resistance across the receiving-condenser 4. The shunt 23 may with advantage be one having a suitable amount of self-inductance. For the purpose of curbing the received current-2'. 6., to separate the slow wave of average currentfrom the sharp waves which constitute the readable signals-I employ, in connection with the receiving-circuit, an inductance-shunt 24, andI adjust the shunt in inductance and resistance to give the correct-shaped signals with a straight zero-line running through them (square signals, as they are called for retransmission. This adjustment of the curbing of the received current can be effected at each receiving end without reference to the corresponding sending end. When condensers are employed in the receiving-circuit, I find the best resistance of the shunt 24 to be about that of the receiving instrume'nt rl. e.,

the recorder-coil. In some cases the sendingcondenser might be dispensed with and the signaling-battery applied direct to the cable. In some cases the receiving-condenser might be dispensed with and the resistance of the self-inductance shu nt 24 greatly red uced. Sometimes in the final adjustment of the ind uctance-shunt of the receiving-circuit I pass through a separate circuit on the receiver-coil a portion of the slow current which flows through the shunt,as illustrated in Fig. 8 in connection with the coil 05 at the intermediate station. Such an arrangement is shown in Fig. 10, in which the inductance-shunt 24 is connected to one of the two coils on the recorder 32". In this manner I effect and control all necessary curbing of the receiver-coil at the receiving-staby cable operators) required 13 on the return of the lever, 11 or 12 closes l tion. The coils of the self-inductance shunts the circuit of the battery 18 through the coils I used in carrying out this invention are someof the relays 14 15 in the reverse direction to 1 times wound with two separate wires and the &

final adjustment of the effective inductance made by closing the circuit of one of the two wires through an adjustable resistance.

As will now be clearly'traced, I provide a complete conductive circuit from the earth at one end (the sending end) through the lowresistance shunt 23 when a sending-condenser is employed, the conductor of the cable, the high-resistance shunt 23, and the receivingcoil d (or, as illustrated in Fig. 8, through a separate circuit on the receiver) to the earth at the receiving'end, and it is by this arrangement, combined with the shunt 24 of low resistance and high self-inductance to the receiving-circuit, as before explained, that I am enabled to obtain the signals shown in Figs. 6 and 7.

The coil (Z of the receiving-relay is shown in one of the positions between the magnets Z; c that it assumes during the reception of a signal; but when no impulse is arriving the contact arm it, mounted on but insulated from the said coil, rests upon the central section 3 of a contact-body a. An arriving impulse has the efifect of movingthe arm it onto one or the other of the outer sections or or a, and it will remain there for a period corresponding to that of the contact made at station I. The two outer sectionsm and z of the contact-body a are connected to the two opposite poles of a split battery 25 26. The coils of the two relays 14 and 15, as in station I, are in series and connected up-one terminal to the tongue it and the other to one of the fixed stops of a relay 27. The tongues of the relays 14 and 15 are connected up in the same way as at station I, and is a similar retransmitting line-battery.

The central section y of the contact-body u is included in a local polarized circuit wherein are the local relay 27, whose contact-tongue 29 rests on the back limiting-stop on the lefthand side when no current is passing through the relay, and separate battery 28. The relay 27 is joined up with the separate battery 28 in such manner that when the tongue it is on the central section 1 of the contact-bod y a the circuit of the battery 28 is closed and the tongue 29 of the relay 27 held over on the opposite contact to that on which it is depicted. On the deflection of the tongue 7L into contact with one of the outer sections 00 or z of the contact-body u the tongue 29 of the relay 27 is deflected, as shown, and the circuit of the two relays 14' and completedthat is to say, the outer terminal of relay 14 is now joined, through the tongue 29 of relay 27,- to the split battery 26, the tongue it being connected to the outer terminal of relay 15, which is in series with relay 14.

A condenser 30 is put across the terminals of the relay 27 in series with a resistance 31 to steady the movements of the tongue 29.

The insertion of the polarized relay 27, shunted with condenser and an adjustable resistance withseparate battery 28 in that part of the local circuit which includes the central section of the contact-body a in the manner above described, has the effect of improving the spacing between the signals retransmitted by the apparatus, and, moreover, when the signal-coil d forms part of the receiving-circuitin a,duplex system there is less jarring of the tongue of the local relay from imperfect duplex balancing than otherwise would be the case.

At station III (assumed to be a terminal station) the impulses are receiving upon a siphon-recorder 32, in which case the signals recorded will be precisely as indicated in Fig. 6. I

In adapting my invention to duplex systems of telegraphy there must be a complete and uninterrupted conductive circuit through the conductor of each section of cable and the receiving instrument from earth at one end to earth at the other end other than through the conductor of the artificial cable 45, and it must be one which is unafiected by variations in the sending-circuit during signaling.

Fig. 9 illustrates one way of arranging the sending and receiving apparatus at each end of every section of cable to permit of duplex working in accordance with this invention. represents the artificial cable. 46 represents the usual low-resistance rheostat. 47 is the receiver-coil of either a siphon-recorder or a recorder-coil relay, as the case may be, and 48 is an inductance-shunt round the transmitter 10. In this duplex arrangement the receiver-coil47 is inserted between theindex-arm of the low-resistance rheostat 46 and earth, and the automatic transmitter 10, with its battery 16 1'6 and sending-condenser 3, are inserted between the cable 1 and the artificial'cable 45. It will be seen that there is a complete conductive circuit from E at both ends of a section through the receiving and sending circuits that is, through the receiving instrument47, a portion of the rheostat 46, the shunt 23 at one end, through the conductor of the cable and the shunts 23, 48, and'24 at the other end, and that this conductive circuit is uninterrupted whatever changes may be made during signaling in the sending-circuit in which the automatic transmitter 10 is placed. On the depression of one or other of the contact-levers 11 12 of the automatic transmitter 10 a'rush of charge into the condenser 3 and the cable from the battery 16 16 takes place, followed by a steady flow through the shunt 23 into the cable, which lasts as long as the contactlever is depressed. At the receiving end the impulse received through the condenser 4 produces a sharp deflection of the receiver-coil 47, which is sustained by the steady flow through the shunt 23 until the cessation of the coritact withbattery at the distant sending enc.

there is no interruption or variation of this When the duplex balance is perfect,

steady received current when contacts with battery at the home end are made, as can be readily understood.

The self induction or inductance shunts illustrated in the drawings accompanying this specification are shown as if constructed with iron cores in order to distinguish them from non-inductance or ordinary doubly wound wire shunts; but I prefer in carrying out this invention to construct all inductance-shunts without iron or other magnetic material.

What I claim, and desire to secure by Letters Patent of the United States, is

1. In a system of electric telegraphy, the combination, with a complete conductive circuit through the conductor of a telegraph-line from the earth at one end to the earth at the other end, of means whereby positive and negative currents of varying duration are applied to the said conductor, and further means whereby deflections of corresponding varying lengths or duration are produced at the receiving end of the line substantially as set forth.

2. The combination, in a system of electric telegraphy, of a conductor, a sending-condenser, a shunt across said sending-condenser, a self-inductance shunt at the receiving end of said conductor, a receiver, and means whereby positive and negative currents of varying duration are applied to said conductor.

3. The combination, in a system of electric telegraphy, of a conductor, a sending-condenser, a shunt across said sending-condenser, a self-inductance shunt at the receiving end of said conductor, a receiver-coil, an extra circuit on the receiver-coil through which a portion of the current that flows through the said self-inductance shunt is diverted for the purpose of assisting in the curbing of the received currents, and means whereby positive and negative currents of varying duration are applied to said conductor.

4. The combination, in a system of electric telegraphy, of a conductor, a receiving-condenser, a shunt across said receiving-condenser, a self-inductance shunt at the receiving end of said conductor, a receiver, and means whereby positive and negative currents of varying duration are applied to said conductor.

5. The combination, in a system of electric telegraphy, of a conductor, a sending-condenser, a shunt across said sending-condenser, a receiving-condenser, a shunt across said receiving-condenser, a self-inductance shunt at the receiving end of said conductor,a receiver, and means whereby positive and negative currents of varying duration are applied to said conductor.

6. The combination, in a system of electric telegraphy, of a conductor, a receiving-com denser, a shunt across said receiving-condenser, a self-inductance shunt at the receiving end of said conductor,

a receiver-coil, an

'extra circuit on the receiver coil through which a portion of the current that flows through the said self-inductance shunt is diverted for the purpose of assisting in the curbing of the received currents, and means whereby positive and negative currents of varying duration are applied to said conductor.

7 The combination, in a system of electric telcgraphy, of a conductor, a sending-condenser, a shunt across said sending-condenser, a receiving-condenser, a shunt across said receiving-condenser, a self-inductance shunt at the receiving end of said conductor,a receivercoil, an extra circuit on the receiver coil flows through the said self-inductance shunt is diverted for the purpose of assisting in the curbing of the received currents, and means whereby positive and negative currents of varying duration are applied to said conductor;

8. The combination, at an intermediate telegraph-station, of two telegraphic conductors one in the receiving-circuit and the other in the retransmitting-circuit, means at the receiving end of the receiving-conductor whereby positive and negative deflections of varying duration corresponding to those originally transmitted are produced at the said receiving end of the line, a recorder-coil relay the coil of which is in the receiving-circuit and its tongue at one end of the retransmitting-circuit, and means whereby positive and negative currents of varying duration are applied to said retransmitting-conductor.

graph-station, of two telegraphic conductors one in the receivlng-circult and the'other in the retransmitting-c1rcuit, a receiving-condenser, a shunt across said receiving-condenser, a self-inductance shunt on the receiving-conductor, a recorder-coil relay the coil of which is in the receiving-circuit and its tongue at one end of the retransmitting-circuit, and means whereby positive and negative currents of varying duration are applied to, said retransmitting-conductor.

10. The combination, at an intermediate telegraph-station, of two telegraphic conductors one in the receiving-circuit and the other in the retransmitting-c1rcuit, a receiving-condenser, a shunt across said receiving condenser, a self-inductance shunt on the receiving-conductor, a recorder-coil relay the coil of which is in the receiving-circuit and its tongue at one end of the retransmitting-circuit, an extra circuit on the receiver coil through which a portion of the current that flows through the said self-inductance shunt is diverted for the purpose of assisting in the curbing of the received currents, and means whereby positive and negative currents of varying duration are applied to said retransmitting-conductor.

I 11. The combination, at an intermediate l telegraph-station, of two telegraphic conducthrough which a portion of the current that 9'. The combination, at an intermediate teletors one in the receiving-circuit and the other in the retransmitting-circuit, aself-inductance shunt on the receiving-conductor, a recordercoil relay the coil of which is in the receivingcircuit and its tongue at one end of the retransmitting-circuit, a retransmitting-condenser, a shunt across said retransmitting-condenser, and means whereby positive and negative currents of varying duration are applied to said retransmitting-conductor. r

- 12'. The combination, at an intermediate telegraph-station, of two telegraphic conductorsvone in the receiving-circuit and the other in the retransmitting-circuit, a self-ind uctance shunt on the receiving-conductor, a recordercoil relay the coil of which is in the receivingcircuit and its tongue at one end of the retransmitting-circuit, an extracircuit on the receiver-coil through which a portion of thecurrent that flows through the said seltFinductance shunt is diverted for the purposeof assisting in the curbing of the received currents, a retra'nsmittingcondenser, a shunt across said retransmitting condenser, and means whereby positive and negative currents of varying duration are applied tosaid retransmitting-conductor.

13. The combination, at an intermediate telegraph-station, of two telegraphic conductors one in the receiving-circuit and the other in the retransmitting-circuit, a receiving-condenser, a shunt across said receiving condenser, a self-inductance shunt on the receiving-conductor, a recorder-coil relay the coil of which is in the receiving-circuit and its tongue at one end of the retransmitting-circuit, a retransmitting condenser, a shunt across said retransmitting-condenser, and means whereby positive and negative currents of varying duration are applied to said retransmitting-conductor.

v 14. The combination, at an intermediate telegraph-station, of two telegraphic conductors one in the receiving-circuit and the other i in the retransmitting-circuit, a receiving-condenser, a shunt across said receivingcondenser, a self-inductance shunt on the receiving-conductor, a vrecorder-coil relay the coil of which is in the receiving-circuit and its tongue at one end of the retransmitting-circuit, an extra circuit on the receiver-coil through which a port-ion of the current that flowsthrough the said self-inductance shunt is diverted for the purpose of assisting in the curbing of the received currents, a retransmitting-condenser, ashunt across said retransmitting-condenser, and means whereby positive and negative'currents of varying duration are applied to said retransmitting-00nductor.

15. The combination, in a system of electric telegraphy, of a plurality of conductors separated by intermediate stations, means serving to apply positive and negative currents of varying duration to the transmitting end of each conductor; a receivingcondenser, a shunt across said receiving-condenser, and a self-inductance shunt on the receiving-conductor serving to curb the received currents at the receiving end of each conductor; a recordercoil relay at each intermediate station,'and a siphon-recorder at the final station.

16. In a system of electric telegraphy, means at an initial station for applying positive and negative currents of varying duration conductor comprising, in,

to the telegraphic combination, an automatic transmitter, a cam, a lever operated by said cam serving to close and open the circuit of a local battery, two polarized relays connected to the two levers of the automatic transmitter and its local battery, and a line-battery brought into action by the tongues of the two polarized relays.

In testimony whereof I have hereunto subscribed my name.

ALEXANDER MUIRHEAD.

Witnesses:

A. F. SPooNnR,

J. S. WITHERS. 

